The regulation of gene expression for yeast genes involved in mitochondrial function will be studied in a two part approach. One approach will focus on the expression of the nuclear cytochrome c gene and its regulation using the purified gene as a probe for transcriptional regulation and RNA processing. An immunoassay for the protein product will be used to study rates of cytochrome c synthesis. The second approach will focus on the transcription of mitochondrial DNA using hybridization studies and an in vitro coupled transcription-translation extract to probe the regulation of mitochondrial genes. With this dual approach, I hope to gain some insight into the coordinate regulation of the nuclear and mitochondrial genomes as a model for DNA-DNA communication across membrane barriers.